Difenoconazole  
ジフェノコナゾール  
 
Standards for Use 
 
Difenoconazole is permitted for use in potatoes . It shall not remain at levels exceeding 
0.004 g/kg of potatoes  as difenoconazole . 
 
Compositional Specifications  
 
Substance Name  Difenoconazole  
Structu ral Formula  
 
 
 
Molecular F ormula  C19H17Cl2N3O3 
Molecular Weight  406.2 6 
Chemical Name [CAS number]  
3-Chloro -4-[(2RS,4RS;2RS,4SR)-4-methyl -2-(1H-1,2,4 -triazol -1-ylmethyl) -1,3-dioxolan -
2-yl]phenyl 4 -chlorophenyl ether   [119446 -68-3] 
Content   Difenoconazole  contains not less than 94.0% of difenoconazole  (C19H17Cl2N3O3). 
Description   Difenoconazole  occurs as  a white to yellow -brown  powder . 
Identification  
Determine the absorption spectrum of Di fenoconazole  as directed in the Disk  Method 
under Infrared Spectrophotometry, and compare with the Reference Spectrum. Both 
spectra exhibit similar intensities of absorption at the same wavenumbers.  
Melting Point   76–83C. 
Purity  
O O
CH3O Cl
ClN
NN 
 
Lead   Not more than 2 μg/g as Pb ( 2.0 g, Method 1, Control Solution: Lead Standard 
Solution 4.0 mL, Flame Method).  
Assay  
Test Solution and Standard Solution   Weigh accurately about  50 mg each  of 
Difenoconazole  and difenoconazole  for assay.  Add exactly  20 mL of the internal  standard 
solution  to each, dissolve by adding acetone  to make exactly  100 mL . 
Internal Standard Solution   Dissolve 75 mg of fludioxonil for assay  by adding 
acetone to make exactly 50 mL.  
Procedure  Analyze 2  μL each of the test  solution  and the standard solution  by gas 
chromatography using the operating conditions given below.  Determine the peak area 
ratios (Q T and Q S) of difenoconazole  to fludioxonil for the test solution and the standard 
solution, respectively. Determine the content  of difenoconazole  by the formula:  
 
Content  (%) of difenoconazole  (C19H17Cl2N3O3) 
= Weight  (mg) of difenoconazole  for assay
Weight  (mg) of the sample × QT
QS ×100 
  
Operating conditions  
Detector: Flame ionization detector.  
Column: A fused silica tube (0. 25 mm internal diameter and 30 m length) 
coated with a 0.25 μm thick layer of dimethylpolysiloxane  for gas 
chromatography.  
Column temperature: Maintain the temperature  at 100C for 1 minute s, raise  
at 30C/minute to 250 C, then raise  at 6C/minute to 300 C, and maintain 
the temperature at 300 C for 2 minute s. 
Injection port temperature: A constant temperature of around  250°C. 
Detector temperature: A constant temperature  of around  300C. 
Carrier gas: Helium.  
Flow rate:  Adjust the retention time of difenoconazole  to about  10–15 
minutes . 
Injection method: Split . 
Split ratio:  1 : 20. 
 
Reagents, Solutions, and Other Reference Materials  
Difenoconazole for Assay  C19H17Cl2N3O3  [119446 -68-3]  A white crystalline powder  
or powder .  
 
Content   Not less than 9 7.0% of difenoconazole ( C19H17Cl2N3O3). 
Identification   Determine the absorption spectrum of difenoconazole for assay as 
directed in the Disk Method under Infrared Spectrophotometry. It exhibits absorptions 
at wavenumbers of about 1605  cm-1, 1585  cm-1, 1507  cm-1, 1478  cm-1, 1227  cm-1, 1048  
cm-1, 848  cm-1, and 679  cm-1. 
Assay   Weigh accurately about  10 mg of difenoconazole  for assay and about 1 mg of 
1,4-BTMSB -d4, and add 1 mL of deuterated acetone to dissolve them together. Transfer 
the resulting solution to an NMR tube of 5 mm in external diameter, an d stopper 
tightly. Measure 1HNMR spectra using a spectrometer with  a proton resonance 
frequency of 400 MHz or more under the following operating conditions. Assuming the 
signal of 1,4 -BTMSB -d4 as 
 0 ppm, when the signal area intensities at around 
  7.33–
7.35 ppm and 
 7.48–7.53 ppm are designated as A 1 (corresponding to 1 hydrogen atom) 
and A 2 (corresponding to 1 hydrogen atom), respectively, confirm that A 1/A2 is 1.0. 
Then, assuming the signal area intensity of 1,4 -BTMSB -d4 as 18.00, when the sum of 
A1 and A2, the sum of the number of hydrogens, and the purity of 1,4 -BTMSB -d4 are 
designated as I, N, and P(%), respectively, determine the content of difenoconazole  by 
the following formula. If the signal from difenoconazole  is overlapped with the signal 
from a contaminant, do not use it s signal area intensity and the  number of hydrogens 
for the assay.  
 
Content  (%) of difenoconazole  (C19H17Cl2N3O3)  
= Weight (mg) of 1,4 -BTMSB -d4 × I × P
Weight  (mg) of the samp le × N × 1.794  
 
Operating conditions  
Digital  resolution:  not more than 0.25.  
Spinning: Off. 
13C decoupling: Present.  
Acquisition time: Not less than 4 seconds.  
Spectral range: At least 20 ppm including between -5 ppm and 15 ppm.  
Flip angle: 90º.  
Delay time: Not less than 64 seconds.  
Dummy scans: Not less than 2. 
Number of accumulation: Not less than 32. 
Measurement  temperature:  A constant temperature  at 20C–30C. 
 
Infrared Reference Spectrum   
 
Difenoconazole